Typically, radio frequency (RF) front-ends of receivers are fed from an antenna providing a single-ended input to the RF receiver chain. For many applications and purposes, however, it is useful to convert the single-ended input from the antenna to a differential signal.
A differential line is a transmission line made of two conductors that both carry a signal with reference to ground. The signals are generally designed to minimize the interference they create together by designing them in such a way that their respective electromagnetic fields cancel each other. For example, the signals may be chosen to be the inverse of each other. In addition, differential signals are robust to interference since interference that is experienced on both conductors, can be removed easily.
To convert a single-ended signal to differential signals, a balun is used, where balun is a word-construct based on bal-anced and un-balanced. Baluns are electromagnetic coupling devices in a wide variety of different possible implementations to achieve the conversion from a single-ended signal to differential signals and vice versa.
Most RF front-ends require the received antenna signal to be amplified by a low-noise amplifier. Hence, the antenna output is fed to a balun to be converted to differential signals. The differential signals are then fed to a differential low-noise amplifier. However, the use of separate discrete devices for the balun and the low-noise amplifier is consuming valuable space, and the performance of the amplifier and the balun cannot be optimized simultaneously.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.